1. Field of the Invention
The present invention relates to a coffee roaster, and more particularly to a coffee roaster, which has a simplified configuration and high heat efficiency by providing a heating means fixed within a rotating drum chamber, thereby improving roasting quality of coffee beans.
2. Description of the Related Art
A process for changing the internal structure of coffee for a predetermined time by applying heat to coffee beans is referred to as roasting, and a coffee roaster refers to a device used to roast coffee. The taste of coffee is determined by the type of coffee beans used and by numerous process parameters, including temperature, humidity, time and so on, during roasting.
In most major brands of coffee, coffee beans are roasted in a large-sized factory using advanced facility and technology and are then packaged to be supplied or distributed to shops that brew and sell coffee. Roasted coffee beans decay in taste and flavor with the lapse of time from the moment roasting is completed. Thus, the best option for enjoying the taste and flavor of coffee is to consume coffee as fast as possible once roasting is completed.
In this connection, the recent trend of coffee roasting is that a vastly increasing number of small-scale cafes having their own roasting machines in their business places, directly purchasing green coffee beans and roasting in only small batches on site for consumption to serve the best quality coffee to their customers with ensured freshness of coffee. Accordingly, there is a rising demand for coffee roasters capable of roasting to meet the trend and demand for better quality of roasting.
A general coffee roaster is known in Korean Patent Application No. 10-2000-27797 disclosing a direct-heating type roaster in which a surface of a cylindrical drum laid in a horizontal direction is heated using a gas burner or an oil burner while rotating the cylindrical drum, roasting is performed using the internal air of the heated drum, and after the roasting is completed, a front door is opened to discharge the roasted coffee beans to a cooling device.
As illustrated in FIG. 1, the conventional coffee roaster includes a front supporting plate 10 having a hull receiving base 11 and a coffee bean receptacle 12 installed thereon, a rear supporting plate 20 including a supply means 21 for inputting coffee beans and an exhaust door 24 for opening or closing a coffee bean exhaust hole 22 by an actuator member 23 and coupled to the front supporting plate 10, a drum chamber 30 installed between the front supporting plate 10 and the rear supporting plate 20 and roasting coffee beans, a first driving member 31 incorporated into the rear supporting plate 20 to rotate the drum chamber 30, a heating means 40 installed in the rear supporting plate 20 to heat the inside of the drum chamber 30, a temperature sensor 50 installed in the rear supporting plate 20 to sense the internal temperature of the drum chamber 30, a transfer conveyor 60 actuated by a second driving member 61 installed in the rear supporting plate 20 to allow the coffee beans discharged from the drum chamber 30 to be evenly discharged into the coffee bean receptacle 12, and a control unit installed in the front supporting plate 10 and controlling a roasting process of coffee beans.
The aforementioned conventional coffee roaster has the following problems.
First, since the conventional coffee roaster is configured such that the drum chamber 30 is entirely rotated, a surface of the drum chamber 30 proximal to the heating means 40 is heated earlier than the inside of the drum chamber 30. Thus, coffee beans being in continuous contact with the surface of the drum chamber 30 may be scorched and only the skin thereof tends to burn without being evenly roasted.
Second, since the conventional coffee roaster is configured such that the drum chamber 30 is entirely rotated, a large driving force is required and the load of the drum chamber 30 is transferred to a rotary shaft, which may adversely affect the durability of the rotary shaft. To avoid this, the first driving member 31 may have increased capacity and size and may make a loud operating noise, resulting in considerable increases in the manufacturing cost and power consumption.
Third, since the conventional coffee roaster is configured such that the temperature sensor 50 is installed to measure only the internal temperature of the drum chamber 30 and the inside of the drum chamber 30 is heated while turning on/off the heating means 40 irrespective of the coffee bean temperature. Therefore, since the coffee beans are not normally roasted, the taste and flavor of coffee may considerably degrade with changes in the temperature and heating time.
In particular, with the temperature sensing structure, it is quite difficult to obtain uniform roasting results, that is, it is difficult to reproduce coffee having the consistent taste and flavor. Therefore, the conventional coffee roaster is difficult to be commercialized to be well-suited for home use or small-scale roasting.